Chemical and physical processes combine to make cells

• Early earth had water vapor and compounds from volcanic eruptions (CO₂, CH₄, NH₃)
  • atmosphere was reducing (now controversial)
  • energy from UV or lightning
  • oceans = primordial soup of organic molecules

• Fossils help divide geologic record into 4 eons

1. Hadean
2. Archaen
3. Proterozoic

4. Phanerozoic: last 500 million years

• Recent geologic ages (3), each with unique animal life

1. Paleozoic
2. Mesozoic
3. Cenozoic

• 2^nd oxygen revolution tied to evolution of animals

• Prior to Cambrian all large animals had soft body
  • little evidence of predation
  • grazers, scavengers, filter feeders

• Large predators evolve in early Cambrian
  • 545-525 mya
  • predator vs prey evolution
  • evolution of eyes

• Spectacular diversification of animals

• Abrupt period: only 10-20 million years!
  • troubled Darwin

• Hard skeletons and soft bodies
  • diverse body morphology (Hox genes)

• Bilaterally symmetrical animals
  • possible formation of ‘head’ region
  • organized sensory organs

• British Columbia’s Yoho National Park
  • 60,000 unique fossils
  • one of the most diverse and well-preserved fossil sites

• Creatures from the Cambrian explosion
  • origins dating 545 to 525 million years ago

• Mudslides from barren land buried marine organisms
  • sediment deposited in deep-water basin next to enormous algal reef
  • soft and hard body fossils

• Continents = floating plates of Earth’s crust
  • plate movement = continental drift
  • a few cm a year

• Landmasses came together 3 times over last billion years
  • yields new continents
  • new super continent in ~250 million years

• Mountains and islands form at boundaries
  • Indian + Eurasia = Himalayan Mtn (45 mya)

• Landmass change alters livable habitats
  • species distributions change
  • oceans change (Valley of Whales)
  • Pangaea (250 mya) drained shallow oceans

• Landmass change alters climate
  • Canada was once tropical

• Continental drift drives speciation
  • adapt, move or die

• 5 mass extinctions in fossil record

  • 50% of marine species extinct

• Permian extinction: 96% marine loss
  • most recent: Cretaceous (bye bye Dino)

• Causes are varied
  • volcanoes & meteors
  • massive climate change
  • ocean chemistry

• Evolution favors innovation but…
  • innovations can be wiped out
  • What if early primates went extinct?

• Define:

• Occur on large scale after extinction events
  • many vacant habitats
  • favors evolutionary innovations

• Innovation leads to diversification

• Dinosaur extinction → mammals
  • small and nocturnal → …